There's a big effort to blame the former Fed chairman for the rise and fall of the housing bubble -- though in fact comparable run-ups in housing prices went on simultaneously in many other advanced countries, with their own monetary policies and systems of housing finance regulation. His response?

The problem is not the lack of regulation but unrealistic expectations about what regulators are able to prevent. How can we otherwise explain how the UK's Financial Services Authority, whose effectiveness is held in such high regard, fumbled Northern Rock? ... Even with full authority to intervene, it is not credible that regulators would have been able to prevent the subprime debacle.

Martin Wolf argues in the FT that central banks "can surely lean against the wind" even if they cannot eliminate bubbles. I know of no instance in which such a policy has been successful.